The productivity and quality of winter whooping crane critical habitat is directly dependent on freshwater inflows
from the San Antonio / Guadalupe River (TPWD 1998). The survival of one endangered species, the whooping crane,
and one candidate species, the Cagle's map turtle, are directly tied to maintenance of inflows (Mendoza 2001b).

The reduction of freshwater inflows is a huge threat to the whooping crane that could lead to extinction. Data
shows that the health and survival of the endangered whooping crane flock is directly related with fresh water
inflows and blue crab populations. Inflows that carry nutrients and sediments are needed to produce blue crabs
that will provide food for whooping cranes.

Data from the last eight winters indicates a direct relationship between freshwater inflows on the Guadalupe River,
blue crab populations, and whooping crane survival. Chavez-Ramirez (1996) found that when available, blue crabs
can make up 80-90% of the diet of whooping cranes. An individual crane can consume up to 80 crabs per day. Studies
by Nelson (1995) of whooping crane food items (crabs, clams, wolfberry, acorns) showed that blue crabs were the
highest in protein and nutrition for the whoopers. When crabs are not available, whooping cranes will switch to
other foods, but because of the poor nutritive value of these alternate foods, the whoopers may actually burn up
fat reserves and have a net loss of energy for periods of the winter (Chavez-Ramirez 1996).

When inflows are high, blue crab populations increase due to enhanced reproduction and survival, and whooping crane
mortality is low. With reduced inflows, crabs do poorly and whooping crane mortality rises dramatically. This makes
sense since blue crabs make up 80-90% of the whooping crane diet. For an eight-year period starting in 1993, surveys
were done to roughly estimate the number of blue crabs available to whooping cranes. The winters of 1993-94 and
2000-01 were poor crab years; the remaining six winters all had adequate numbers of blue crabs present. During
the two winters with poor crab numbers, seven and six whooping cranes died respectively. In all six other winters,
either zero or one whooper died. Thus, there seems to be a strong inverse correlation between blue crab abundance
and whooping crane mortality. Sufficient inflows are required to produce the necessary food for
whooping cranes to survive. Higher winter mortality of whooping cranes occur when blue crab numbers are low, therefore
the very survival of the species is dependent on water management strategies that provide inflows for the bays
to remain productive (Mendoza 2001a). In addition, following the poor blue crab winter of 1993-94, 37 % of the
known adult pairs (17 out of 46) failed to nest following their return to Canada. This was believed to have resulted
from their decreased energy reserves that had not built up sufficiently during the previous winter. This was unusual
since normally just about all pairs attempt to nest annually.

Inflows which mix with Gulf waters help keep salinity levels moderate. When marsh and bay salinities exceed 23
parts per thousand (ppt), whooping cranes are forced to make daily flights to freshwater to drink. These flights
use up energy, reduce time available for foraging or resting, and could make the cranes more vulnerable to predation
on the uplands (Stehn pers. comm.). Thus, inflows are crucial in keeping salinity levels below the threshold of
23 ppt in coastal marshes used by whooping cranes .Status of Guadalupe River flows
Inflows on the Guadalupe River are already insufficient and reduced over historic levels. TWDB data indicate natural
droughts already threaten the ecosystem of the Guadalupe Estuary and predict that in less than 50 years withdrawals
of surface and ground waters for municipal and industrial growth will leave insufficient inflows to sustain the
ecosystem (USFWS 1994).

Kretzschmar (1990) predicted that a net annual loss of gaged inflow amounting to 555,000 acre-feet of water would
occur on the Guadalupe by the year 2040. As water development pressures mount, freshwater inflows to the Texas
bay systems are being reduced, and blue crab populations are being adversely affected. TPWD projects an 8 % reduction
in blue crab populations in 40 years due to reduced inflows. This is going to have an alarming impact on whooping
cranes.

The San Antonio and Guadalupe Rivers that empty into whooping crane critical habitat are calculated to need 1.24
million acre-feet per year to maintain ecosystem subsistence (TPWD 1998). Yet between 1941-1976, inflows were less
than that amount in 14 out of 36 years, making its status already precarious (TDWR1980). The Service is very concerned
about the impacts that planned diversions from the Guadalupe River would have on environmental water needs for
adequate inflow to San Antonio Bay. Reduced inflows, including planned diversions from the lower reaches, is a
definite threat to the continued survival of the wintering population of the endangered whooping crane and its
critical habitat which lies in and around this estuary. With projected diversions, inflows will be insufficient
to maintain the ecosystem in an average rainfall year (Stehn pers. comm.). Long before the ecosystem collapsed
for lack of inflows, there would be significant adverse impacts to the primary winter food supply of the whooping
crane (Kretzschmar 1990). The death of 6 whooping cranes during the 2000-01 winter emphasizes how serious an issue
this is. This projected reduction is a major concern in keeping the whooping crane from going extinct (Stehn pers.
comm.).

Human consumption of river water in Texas is a growing resource issue as the State's population continues to expand.
This is a very worrisome trend since Texas water law reserves water for people but has few provisions for wildlife.
Leaving sufficient water in the rivers to provide bay inflows is not explicitly designated as a beneficial use
of water in Texas water law. National media attention was received in spring 2001 when the Rio Grande River dried
up and flows no longer reached the Gulf. This is not the only river in Texas in trouble. So many people are using
water from the aquifer and the rivers in central Texas, that the downstream folks and creatures are already seeing
what most Texans do not want to acknowledge; that the rivers are already over-appropriated, and absolutely noone
is minding the store, when it comes to making sure any fresh water ever makes it to the bays and estuaries (Wassenich
pers. comm.).

With the population of Texas predicted to double in the next 50 years, the Texas legislature has initiated a state-wide
water planning effort. As water developers plan to take water from the rivers, there is no direct mechanism in
Texas water law to secure freshwater inflows to the bays and estuaries. Basically, the bays get whatever is left
over, and portions of Texas rivers, including the Guadalupe, are already over-appropriated.

To prevent impacts and avoid "take" of the whooping crane under the Endangered Species Act, the Service
urges planners to quantify the freshwater inflow needs to maintain bay productivity and the critical habitat of
the whooping crane and to account for these needs in future versions of the State Water Plan (Mendoza 2001b). Formal
consultations on flow reductions must ensure that downstream water needs are met (Stehn 1998).

Management Actions and Needs
The San Marcos River Foundation has applied for a 1.3 million acre-feet water right that would remain in the rivers
to provide inflows to the bay. This amount is the minimum flow needed to sustain the bay ecosystem and keep the
bays productive (TPWD 1998, Mendoza 2001a). Without sufficient inflows, wildlife resources, including fish, crabs,
and shrimp, all decline. The 1.3 million acre-feet figure is often quoted as an amount needed to maximize harvest
of 9 marine species of commercial interest in the bays and estuaries. In the case of blue crabs, more than 1.3
million acre-feet is needed to produce high blue crab populations. TPWD data clearly show that increased water
inflows result in higher blue crab numbers (Mendoza 2001a). Crab survival of all life stages increases when salinities
are generally below 20 ppt, and the very young stages in the blue crab life cycle show much better survival when
salinities are moderate. Blue crabs were found to be more abundant in the Guadalupe Estuary in salinities averaging
between 10-25 ppt. A simple inverse relationship exists between blue crabs catch rates and mean salinity within
an estuary (Longely 1994). Peak crab counts in the bays occur following periods of flooding. In San Antonio bay,
the 3 highest blue crab harvest years were all having inflows greater than 3 million acre-feet annually. Thus,
to maximize blue crabs for whooping cranes to eat, managers should maximize freshwater inflows on the Guadalupe
River. Guaranteed minimum inflows to the bay are essential. Inflow level targets have not been identified to adequately
support whooping cranes.

Any withdrawal of water from the San Antonio / Gaudalupe River system is harmful to whooping cranes (Stehn pers.
comm.). Inflow modeling is needed specifically for impacts to blue crab populations. Until this is done, water
planners cannot make a judgement how much harm river withdrawals will do to blue crabs and thus whooping cranes.
The U.S. Fish and Wildlife Service believes that providing a water right to the bays, as proposed by the San Marcos
River Foundation, would be a crucial first step in guaranteeing that the bays would continue to function ecologically
for all users to enjoy (Mendoza 2001a).

The U.S. Fish and Wildlife Service must take a strong stand on the inflow / whooping crane issue. All conservation
groups need to do all in their power to ensure that adequate inflows from the Guadalupe River reach the bays. The
Service has written a letter of support for the San Marcos River Foundation's application for 1.3 million acre-feet
of water that would remain in the river for wildlife. The San Marcos River Foundation's water rights application
is an important step in ensuring inflows on the Guadalupe reach the bays. It would be precedent setting in Texas
for a water right to be designated as an inflow. Water developers are contesting the application. They are saying
that human needs for water are too great and that there isn't enough water available to provide the water identified
by the Texas Parks and Wildlife Department study needed to sustain the bays and estuaries. This issue has everyone's
attention, and support is needed if the San Marcos River Foundation's application is to be successful.

Measures to protect instream flow, fish and wildlife habitat, and freshwater inflows to bays and estuaries should
be part of each regional water management plan (Sansom 2000). It is essential that the Region L water plan provide
a mechanism for providing adequate inflows to San Antonio bay for the health and survival of the whooping crane
population.

Any environmental analysis for groundwater use should include a detailed assessment of potential impacts to fish
and wildlife found in springs, streams, rivers, and even inflows to bays and estuaries. An example of an area of
concern is the Edwards Aquifer and the impacts reduced flows would have on the whooping crane found in the San
Antonio and Aransas bays (Mendoza 2001b). Especially in times of drought, groundwater-fed springs can provide 80%
of the inflow from the Guadalupe River. Comal and San Marcos Springs combined can make up over 30% of the base
flow of the Guadalupe River and nearly 70% during periods of drought (Sansom 2000).

Management actions needed are to

a) model inflows and blue crab populations for the Guadalupe Estuary and relate to ecological needs of whooping
cranes.